The polyamine putrescine, spermidine, and spermine are major cellular components of all living cells and have been shown to be involved in many systems related to growth and differentiation. Our current and older studies have been directed at learning how these polyamines are synthesized and regulated and their physiological function in vivo. As part of these studies we are currently concentrating on the biochemistry, regulation, and genetics of these amines in Saccharomyces cerevisiae. In our past studies, we prepared mutants in the biosynthetic pathways and showed that cells that were deprived of spermidine or spermine were unable to grow, to sporulate, or to maintain the virus-like RNA killer plasmids of yeast. Our current studies have demonstrated two additional in vivo functions: (1) Spermidine protects yeast from oxidative damage due to superoxide formation. (2) We have also shown an unusual and unexpected effected of spermidine on protein synthesis in vivo. With the use of a model system for the study of ribosomal frameshifting, described by Wickner and Dinman, and in collaboration with them, we have shown that polyamine are essential for the maintenance of the correct translational efficiency of +1 ribosomal frameshifting. Ribosomal frameshifting is of particular importance the development of retroviruses and is known to be important in the "gag-pol" type of protein synthesis in the L-A dsRNA system of yeast studied by Dinman and Wickner and in the Ty suppressor mutations that overcome mutations in the biosynthetic pathway for the amines and on the regulations of the steps in this pathway.